Shock Absorbers and Strut Inserts
The shock absorber or strut inserts function is to dampen the oscillations or bouncing caused by the suspension coils passing over bumps in the road. Testing a shock absorber's ability to return to normal is done by pressing downward on the bumper at the side with the weak shock. Be careful not to damage the bumper.
A good shock absorber quickly comes to rest and returns to normal. A faulty shock or strut would continue to bounce. It's because the weak shock absorber allows the coil spring to continue to oscillate.
Bad shocks and struts cause cupped tires. Jounce the front end to see if it oscillates and test drive the vehicle to see if it floats and leans excessively around corners. Tire wear can also indicate a worn steering or suspension component, an over or under-inflated tire, or a misaligned vehicle.